Electrical energy/electricity is presently predominantly supplied via grid connections that are permanently assigned to a property. These grid connections are permanently assigned to a power customer. Stationary energy meters are permanently installed for measuring, metering and rendering an account of the electrical energy/electricity drawn off via the grid connection. An account of the electrical energy/electricity drawn off or fed in via the grid connection is thus rendered to the power customer. No differentiation is made as to which person or which user draws off energy/electricity at each measured connection.
DE 695 09 529 (EP 0 769 218) describes a distribution network and suggests a solution to the problem of enabling accounting with respect to an individual subscriber that is not bound to a fixed geographical point, as disclosed, e.g., in SE 425 123, U.S. Pat. No. 4,352,992 or EP 0 047 089.
DE 695 09 529 describes a distribution network comprising electric wires, a plurality of tap-off facilities with at least one socket means for tapping off electric current and a computer unit communicating with the individual tap-off facilities over the power supply. As far as switchable, these tap-off facilities are connected on the power connecting side with a so-called regulating device for identifying the user and switching the socket means.
The operator connecting a power-consuming unit to the tap-off facility is identified by the computer unit connected to the tap-off facility or the regulating means via a microprocessor installed in the power-consuming unit. Thus, in the system described in this document, the operator or power-consuming unit is identified by the tap-off facility or the central computer unit connected thereto. This is only possible since the tap-off facilities of the distribution network described in DE 695 09 529 are connected to computer units that are installed for this very purpose, since according to the invention disclosed in this document the tap-off facilities (in combination with the respective central computer units) must be capable of providing or retrieving information on the tap-off facility itself and, additionally, any information on all system users. According to DE 695 09 529, the identification process allowing the operator to draw off electricity by switching the regulating means is realised by communication between a computer unit installed for one or a small number of tap-off facilities for this very purpose and the tap-off facility, via signals superimposed on the distribution network. The distribution network according to the invention utilises the power line communication between the computer unit and the tap-off facility.
EP-A-2 192 386 discloses a metering and measuring point system for metering and measuring electrical energy consumption or generation. The system comprises a number of stationary drawing off devices that are connected to the power supply and configured for drawing off or feeding in electrical energy by means of consumption and/or generation units. These drawing off devices are tagged with an identifier enabling the identification of the grid connection holder. The system is moreover provided with at least one identifiable non-stationary functional unit for measuring and metering electrical energy that is drawn off or fed into one or more stationary drawing off devices by consumption and/or generation units via an electric conductor. The non-stationary functional unit comprises a device for detecting the identifier of the drawing off device, an identifiable device for metering and measuring the electrical energy drawn off and/or fed into the detected drawing off device, a device for storing the detected metering and measuring data as well as the detected identifier of the respective drawing off device and a device for reading out the stored data.
The metering and measuring point system described in EP-A-2 192 386 is i.a. characterized by a non-stationary, mobile metering technology. This system provides numerous advantages with respect to the costs of the connection points and thus the costs for the entire infrastructure. However, the mobile metering technology—e.g., in a vehicle—could also involve a certain attack scenario:
The attacker of the system does not only connect the registered system user to the de-energised drawing off device (which is thus at first protected against electricity theft), but instead connects several users to the drawing off device—for example by means of a Y-cable or any other device. Upon a successful authentication of the registered user, the drawing off device is energised. Electricity is then drawn off by all connected users, but since the meter is mobile, only the electricity drawn off by the registered user over the connected branch wire is metered. Thus, the other users take advantage of the activation by the legitimised user, more or less according to the “piggyback” principle, without the electricity they draw off or feed in being metered. By such a manipulation, an equitable allocation and rendering of account of the drawn off current to the user could consequently be circumvented.